Various quaternary ammonium compounds are known in the art to possess antistatic properties. These quaternary ammonium compounds are also known to be generally incompatible with anionic surfactants commonly employed in laundering compositions. The anionic surfactants attack and inactivate the quaternary ammonium compounds in the wash-water environment. Thus, larger amounts than desired of the fairly expensive quaternary ammonium compounds must be added to detergent compositions in order to avoid total inactivation in wash solution. It therefore would be highly beneficial, from a performance and economic standpoint, to be able to shield the quaternary ammonium compounds in the wash water, without disturbing their effectiveness as static control agents in the subsequent machine drying process.
Techniques known in the art for preserving the antistatic properties of the quaternary ammonium compounds, such as the prilling of the quaternary ammonium compound with organic dispersion inhibitors, as disclosed in U.S. Pat. No. 3,936,537, issued to Baskerville et al on Feb. 3, 1976, incorporated herein by reference, and the agglomeration of that prill with certain water-soluble neutral or alkaline salts, using organic agglomerating agents, as disclosed in the copending application of McDanald, Ser. No. 816,761, filed on July 18, 1977, now U.S. Pat. Ser. No. 4,141,841, issued Feb. 27, 1979 incorporated herein by reference, while delivering improved static control and softening benefits over methods then known in the art, were only partially effective. Some of the quaternary ammonium compound continued to be inactivated by the anionic surfactants, and some of the prills continued to be broken up and dispersed in the wash water, preventing the efficient desposition of antistatic materials of an effective size range onto the fabrics to be treated. The above-described techniques still required the addition of larger quantities of the quaternary ammonium compound than necessary to achieve good static control in the absence of the detergent. Also, the conventional organic agglomerating agents, such as dextrin glue solutions, required in McDanald to agglomerate the prills with the salts could cause poor caking characteristics and flowability problems in the detergent product, making handling and packaging difficult at times.
The present invention, by contrast, teaches the deliberate, pre-wash-water complexing of certain anionic components with the quaternary ammonium compounds to deliver superior static control and softening benefits at significantly reduced levels of antistatic material. The Baskerville and McDanald references attempted to avoid the interaction of anionic components with the quaternary ammonium compound upon which the present invention is based. Further, it has been discovered that water can act as the agglomerating agent and/or the complexing medium, while producing a product with at least equivalent caking charcteristics, and even superior caking qualities under certain conditions. Thus, the organic agglomerating agents required in McDanald have been eliminated in the present invention, reducing material costs and eliminating extra processing and handling steps.
It is, therefore, an object of the present invention to provide a particulate additive for laundry detergent compositions to reduce the tendency of fabrics washed with such detergent compositons to generate or retain static electricity when subjected to a subsequent machine drying process.
It is also an object of the present invention to provide a detergent composition capable of concurrently laundering, softening, and imparting static control benefits to fabrics washed therewith and subsequently machine dried.
It is another object of the present invention to provide a particulate antistatic fabric-softening additive which can be included in a conventional detergent composition and which will retain its effectiveness in softening fabrics laundered therewith in a subsequent machine drying process.
It is a further object of the present invention to provide for antistatic fabric-softening effectiveness by using a minimum amount of antistatic fabric-softening agent in a detergent composition.
It is another object of the present invention to provide an antistatic, fabric-softening detergent additive which will remain relatively homogeneously admixed in a conventional detergent composition.
It is an even further object of the present invention to provide a detergent composition with good caking and flowability characteristics.